I did bring sample images in once but leonard-talk started and the rep would tell me about the standard procedures and line chart that Nikon uses to test AF. I feel that they are not doing anything (yet) because they don't want things to be blown out of proportions... furthermore some senior techs at sendai factory will get the beating for sure.

If I were in your position, I wouldn't even bother bringing sample images. They didn't see them being taken, so they can say all sorts of things about clumsy technique, improper AF fine tune calibration, or so on. Well, I might bring one or two real world images showing how badly the problem affects results.

What I would do is to actually take the camera itself into the conversation. As soon as that talk about whether the problem actually exists starts, I'd take the camera out of the bag, mount a lens on it, and give him a demonstration.

I'd focus on a subject using the leftmost point in AF-S mode several times, and show him (via image review) that each time, the subject comes out OOF even though the camera clearly confirmed focus and the right AF point was clearly selected (visible in image review as a red box over the subject). Then, I'd focus/recompose using the center point, or use live view CDAF, and show him just how much of a difference that left point focus inaccuracy makes. And finally, I'd take some pictures using the center focus point to show that I've already done AF fine tune, and explain that adjusting AF fine tune to the left point would throw off my center point, and so on.

It's easy to deny that equipment is at fault when only sample images are in question. After all, there are a ton of factors in any scenario that could cause focus inaccuracy. But I think it'll be pretty convincing if you demonstrate the problem right there.

This won't work. I have done the same thing with the AF assist beam from SB900, and confirmed the focus shift problems on various camera bodies, lenses and speedlights (even theirs for demonstration) at Nikon UK. They told me everything is within Nikon's standard and they can do nothing about it. They told me to shoot at f4.

I've had a rep who attempted to help me with the 35 1.4G focusing issues... after a week he showed me pictures which he took, stating it was perfectly fine, when i checked out what aperture he used, he said f2.8. I gave up talking to him after he slandered me to a senior photographer, I was sitting across the room behind the wall and actually heard it and I confronted him. He swiftly proceeded into the office while saying "non of my business, non of my business".